Ultrasound probe

ABSTRACT

A body (40) is provided which is inserted between an ultrasound crystal (30) and an output port (27) in a probe filled with a fluid, to centrally defocus generated ultrasound and create an output ultrasound field having limited propagation, especially for higher intensities, after passing the output port. The casing is divided into three portions (21, 22, 23), whereby a front conical portion (21) including the output port (27) and the centrally defocusing body (40) is easily replaceable. The fluid in the casing is refilled via a tube connection (12) to a fluid storage connected as a communicating vessel to the ultrasound device. Moreover, the output port of the device is provided with a thin membrane (10), preferably of replaceable latex rubber, which is attached to prevent the fluid in the casing from emerging, but at the same time enabling the effective transfer of generated ultrasound. The membrane (10) may be attached by placing an O-ring gasket in a circularly formed slot (25) on the conical portion.

TECHNICAL FIELD

The present invention relates to an ultrasound probe, and particularlyto a defocusing device for an ultrasound generator forming anddelimiting an outgoing ultrasound field, for instance in the field ofmedical applications.

PRIOR ART

In connection with the treatment of glaucoma, there is a general desireto treat this disease without necessarily resorting to direct surgicaloperation on the eye. It is known that in a glaucoma condition, smallparticles are gradually clogging the filter, which forms the so calledtrabecular meshwork, thereby increasing the pressure in the eye causedby the continuing building up of the eye aqueous fluid, that can not bedrained in a natural manner, thus causing harmful pressure to the eye.Apart from the usual treatment by means of using various kinds of eyedrops, there are a number of patent documents describing differentinstruments for the treatment of glaucoma, to mention among others WO91/12046 and WO 93/20783, which are related to transplantation of adrainage device into the eye, to in an artificial manner control thepressure in the eye. A number of documents, for example U.S. Pat. Nos.4,928,697 and 4,945,913 describe devices used to measure the pressure inthe eye without making direct contact to the eye itself. Furthermorethere are other devices described which comprise ultrasound probes whichare surgically applied into the eye to remove unwanted tissue. Examplesof such devices are: U.S. Pat. No. 3,528,410, U.S. Pat. No. 3,857,387and U.S. Pat. No. 3,942,519.

A new method, which recently has been proposed, is based upon by meansof ultrasound having a specially designed field form generated, so tosay, to from outside the eye shake out the particles clogging thedrainage path of the eye aqueous fluid. In order to achieve this, anultrasound probe is required being able to produce a suitable ultrasoundfield, which may be concentrated just around the trabecular meshworksuch that during the treatment it will not affect or damage other partsof the sensitive eye.

There are known many different forms of ultrasound generators. Examplesof such generators appear for instance in the German patent documents:DE 945 417, DE-1 120 784, DE-4 011 017, DE-4 034 533, DE-4 122 590 andDE-4 136 004. The first one of these generators (DE 945 417) wasdisclosed already in 1956, while the last one (DE-4 136 004) dates backto 1991. DE 945 417 discloses an absorption cover, preferably of feltedmaterial which can attenuate production of standing waves. DE-1 120 784discloses a membrane consisting, for example, of an electromechanicalactive ceramic material, like barium titanate, for transmission ofultrasound waves from the generator to a medium.

DE-4 011 017 discloses a device for generating focused shock wavesprovided with two-sided shock wave sources, whereby the sources are ofdifferent types and focusing takes place by moving the sources inrelation to each other.

From the last three mentioned patent documents (DE-4 011 017, DE-4 122590 and DE-4 136 004) DE-4 034 533 discloses a shock wave source withfocusing of the generated pressure pulses to a convex lens serving as afocusing zone, whereby the upper face of the convex lens forming theoutput sound surface presents a form different from the necessary formfor focusing of the pressure pulses.

DE-4 122 590 additionally discloses a shock wave generator having afocusing means, whereby at the same time there are means, the defocusingaction of which is adjustable and less than the action of the focusingmeans. The disclosed design is primarily intended for splitting up renalstones whereby its purpose is to create a considerably larger focusingzone in order to manage splitting up large stones. This design is notapplicable for the treatment of the eye according to the suggestedmethod.

Finally DE-4 136 004 discloses a generator for generation of acousticwaves with a liquid lens adjusting the focal distance and thereby movingthe focal point of the acoustic waves. The design moreover discloses acomplicated construction which is not applicable for the purpose oftreating eyes according to the suggested method.

DESCRIPTION OF THE INVENTION

According to the present invention, an ultrasound device is disclosed,which can generate an adapted ultrasound field, applicable, for example,in an suggested method for treatment of glaucoma, which device can bedirected towards the trabecular meshwork of an eye without affecting orharming the other parts of the sensitive eye in such a treatment.

According to a first objective of the present invention, a body isinserted between the ultrasound crystal and an output port of the fluidfilled portion of the device in order to centrally defocus the generatedultrasound and provide a reduced ultrasound field having a limitedpropagation of primarily higher intensities after passing the outputport.

According to a second objective of the present invention, the casing isdivided into several portions, whereby a forward conical front portion,including the output port and the centrally defocusing body, is easilyreplaceable, whereby fluid in the probe is refilled via a tube jointconnected to a liquid storage acting as a communicating vessel to theprobe.

According to a third objective of the present invention, the output portis provided with a thin replaceable membrane, preferably of latexrubber, fixedly held by an fixing means to prevent the fluid fromemerging, but at the same time enabling effective transfer of thegenerated ultrasound, whereby the fixing means consists of an O-ringgasket placed in a circular slot of the conical portion.

Further objectives and purposes of the present invention are set forthbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in form of a preferred illustrativeembodiment by means of the attached drawings, wherein same referencenumbers indicate equal or corresponding members, and where:

FIG. 1 demonstrates an illustrative embodiment of an ultrasound probeaccording to the present invention;

FIG. 2 demonstrates a cross section of a disassembled ultrasound probeaccording to FIG. 1;

FIG. 3 demonstrates a front view of an illustrative embodiment of adefocusing member according to the present invention; and

FIG. 4 demonstrates an enlarged cross section view of the adjustmentdevice of the ultrasound probe.

DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT

FIG. 1 presents an illustrative embodiment of an ultrasound probeaccording to the present invention. The probe, totally designated as 1,presents a casing 2 consisting of three portions, according to FIG. 2, afront conical portion 21, a central portion 22 provided with a tubeconnection 12, and a rear portion 23 provided with a coaxial socket 14,preferably of type BNC. The front conical portion 21 additionally, inits outer conical surface, is provided with a circular slot 25 in orderto receive an O-ring gasket 11. The O-ring gasket is used to secure inposition a membrane 10, preferably a portion of a condom, to flexiblyclose a front opening port 27 of the front conical portion 21.

Between the central portion 22, which is threaded into the rear portion23, an ultrasound crystal 30 is inserted, the center of which will thenabut a spring biased electrically conducting plate 31 through a spring32 electrically connected to the center pin of the BNC socket 14.

The tube connection 12 onto the central portion 22 is connected by asuitable flexible tube to a fluid storage (not shown), preferablycontaining distilled water.

Thus the portions 21 and 22 of the assembled device, are filled withfluid acting as transmission medium for the ultrasound waves, which areelectrically generated by means of the crystal 30. The very thinmembrane 10 covering the opening 27 prevents the fluid from emerging,but does not prevent the generated ultrasound waves from propagatingfurther through the opening 27 towards an outer medium in contact withthe membrane.

The crystal 30, which preferably in the preferred embodiment normallyhas a thickness of about 0.5 to 0.9 mm abuts the outer edge of the sidefacing the conical portion 21 and against a slightly inclined flange 33in the central portion 22, and which is adopted to the crystal 30. Theflange 33 is then arranged to make electrical contact with the side ofthe crystal facing the conical portion and thereby connecting it to theouter sleeve of the BNC socket. The flange 33 also centers the crystal30 in the device. To electrically make connection, an electricallyconductive material is used which at the same time serves as sealingsubstance to prevent the space behind the crystal 30 from being filledwith fluid.

For instance, in a preferred embodiment of the ultrasound probe,preferably a nylon or teflon ring (not shown) is positioned against thecircumferential edge of the crystal 30 at the side facing the BNC socketand which ring further is pressed against the crystal 30 by a stronghelical spring (not shown) and which has an external diametercorresponding to the internal diameter of the rear portion 23. Rearportion 23 contains a power connection to an active driven electrode ofthe ultrasound crystal (30). By means of this latter arrangement, thecrystal is ensured to maintain its position during operation and that noliquid may leak into the rearmost space area. Moisture eventuallyleaking will, according to the state of the art, be detected by theelectronic unit feeding power to the crystal 30.

Additionally there is, inside the conical portion 21, centered a body40, preferably made of rubber. In the illustrated embodiment the body 40has the form of a cone with rounded top, and it is centered with greatprecision in the conical portion 21 by means of three beams 41. In theillustrative embodiment the beams 41 or thin stable booms are made ofthin injection needles which have a small spacing rivet soldered at theends facing the body 40, the rivet defines exactly how deep the beamsshould reach into the, in advance designed, fastening holes in the body40 to guarantee a good centering therein. The other ends of the threebeams 41, according to the disclosed embodiment, are attached to theinner wall of the conical portion 21.

The conical portion 21 is attached to the central portion 22 by athreaded attachment, whereby an oval O-ring gasket 50, shown enlarged inFIG. 4, seals the connection between the two sections 21 and 22. TheO-ring gasket 50 is made oval to allow an exact adjustment of theconical portion, and thereby the body 40, relative to the crystal 30.The oval cross section of the O-ring 50 allows a position rangevariation of about 1 mm between the portions 21 and 22 with a retainedsatisfactory sealing quality. In FIG. 2 and 4, 51 designates a clearancezone for the conical portion 21.

The device, according to the illustrated embodiment, may operate withreplaceable conical portions 21, which, for example, may have differentlength and/or different sized output opening, and/or a different body40. In a preferred embodiment of the present invention the opening 27 ofthe conical portion 21 is slanted about 10°-15° (not seen in FIG. 2)relative to the longitudinal axis of the conical portion 21 to obtain aneasy application of the device to the area middle over the trabecularmeshwork of the eye. Even a larger slanting of the opening 27 could beadvantageous in a particular operation with the device. Beforeutilization, the portion 21 will be assembled to the rest of the casingand a fluid connection is made to a storage container, for instance aplastic bag filled with distilled water or saline. Such liquid bags arewell known in the technical field. By keeping the device 1 at a suitableheight in relation to the liquid bag, fluid will flow into the device 1.The device should preferably be held with its opening 27 directed upwardso that when the device is fully filled, the water will be pressed outthrough the opening 27. By properly balancing the height, as statedabove, and utilizing the fluid surface tension, fluid is obtained allthe way out to the discharge opening of the portion 21, and thus, allair has been evacuated from the device. At this point, a piece of latexrubber, in the simplest case a piece of a condom, will be placed overthe opening 27, and the latex rubber will be tightened over the conicalportion by means of rolling upwards a suitable O-ring gasket 11 until itlocks into the slot 25.

At this stage, the device is ready for use after, in addition, the tipof the conical portion 21 preferably has been provided with a smear ofgel to be able to transmit the ultrasound to an area, middle over thetrabecular meshwork of the eye, to be treated.

In a case when the device will be used for the treatment in connectionto glaucoma, the tip having the gel is placed carefully to the areamiddle over the trabecular meshwork and the crystal 30 is powered andthereby an ultrasound field is obtained, the energy of which isintended, only of an order of 0.6 to 1 mm, to be active into the eye,according to the present state of the art. The probe 1 is then movedcarefully around the iris along the trabecular meshwork.

Thus the desired effective field pattern of the active ultrasound isobtained through the combination of the shape of the conical portion andthe form of the body 40 and its central position in front of the crystal30 according to the present invention, whereby a direct wave from thecrystal is restricted from propagating through the opening 27 and intothe eye, where such a wave could reach too deep and even could beharmful. A number of standard portions 21 could be manufactured, basedon the medical requirements for field patterns of the ultrasound.

The ultrasound device according to the present invention can of coursebe modified in various ways by a person skilled in the art withoutdeparting from the spirit and scope of the invention as being defined inthe attached claims.

What is claimed is:
 1. An ultrasound probe (1) for generating anultrasound field, comprising a casing (2) having a liquid-filled innerspace, liquid in said liquid-filled inner space allowing the propagationof an ultrasound field, and an ultrasound crystal (30) mounted in thecasing (2), the ultrasound crystal being powered by a source ofelectricity which is connected to the ultrasound crystal by a socket(14) mounted on the casing (2), the ultrasound crystal delimiting theliquid-filled inner space in one direction and generating the ultrasoundfield, the casing (2) further comprising an output port (27), and theultrasound probe further comprising a body (40) arranged in theliquid-filled inner space between the ultrasound crystal (30) and theoutput port, for centrally defocusing a generated ultrasound field. 2.Ultrasound probe according to claim 1, wherein said body (40) is mountedradially centered with respect to the casing (2) by thin stable booms(41) connected to an inner surface of the casing (2).
 3. Ultrasoundprobe according to claim 1, wherein said body (40) is a conical body ofcast rubber, said conical body having a rounded tip.
 4. Ultrasound probeaccording to claim 1, wherein the casing (2) is divided into a number ofportions (21, 22, 23), of which a front conical portion (21) includesthe output port (27) and is removably couplable to a central portion(22) by threads provided on the front conical portion and the centralportion, and wherein the casing (2) comprises a tube connection (12) forrefilling the casing (2) with liquid, said tube connection beingconnectable to a liquid storage means in such a way that the casing andsaid liquid storage means function as communicating vessels. 5.Ultrasound probe according to claim 4, wherein said output port (27)comprises a replaceable membrane (10) secured onto the front conicalportion by a rubber O-ring (11) fitted into a locking groove provided onan outer circumference of said front conical portion (21), whereby saidmembrane prevents liquid from emerging at said output port yet enablesan effective transfer of generated ultrasound.
 6. Ultrasound probeaccording to claim 4, wherein connection between said front conicalportion (21) and said central portion (22) of the casing (2) is providedwith sealing means (50) for enabling fine adjustment of the distancebetween said output port (27) and the ultrasound crystal (30), whereby acoupling between said front conical portion and said central portion isachieved by complementary threading of the respective front conicalportion and said central portion.
 7. Ultrasound probe according to claim4, wherein said body (40) is mounted radially centered with respect tothe casing (2) by thin stable booms (41) connected to an inner surfaceof said front conical portion (21).
 8. Ultrasound probe according toclaim 2, wherein the ultrasound crystal (30) abuts against said centralportion (22) of the casing (2) in such a way that a liquid-tight seal isachieved, thereby preventing liquid from penetrating into a rear spacein a rear portion (23) of the casing (2), and further wherein said rearportion (23) contains a power connection to an active driven electrodeof the ultrasound crystal (30).
 9. Ultrasound probe according to claim1, wherein said output port (27) is an opening in said front conicalportion, said opening being angled relative to a longitudinal axis ofsaid front conical portion, whereby in use said angle of said openingpermits an inclined position of the ultrasound probe.
 10. Method fortreating a glaucoma condition by using ultrasound, comprising the stepsofselecting an ultrasound crystal (30) mounted in a casing (2), poweredby a source of electricity connected to the casing; providing, in thecasing (2), an output port (27) for transmitting therethrough ultrasoundwaves generated by the ultrasound crystal; providing, in a space betweenthe ultrasound crystal (30) and said output port (27), a liquid fortransferring the ultrasound waves generated by the ultrasound crystal(30) to the output port (27); providing, in the casing, a radiallycentered body (40) between the ultrasound crystal (30) and the outputport (27), for centrally defocusing the ultrasound waves; and arranging,over the output port (27) of the casing (2), a membrane (10) forpreventing liquid in the space between the crystal (30) and the outputport (27) from emerging from said output port (27), and for transferringthe ultrasound waves from the output port (27) to an object brought intocontact with said membrane (10).
 11. Method according to claim 10,comprising the further steps ofapplying a suitable gel to the membrane(10); bringing said membrane (10) with the suitable gel into contactwith an area located over the trabecular meshwork of an eye; andenergizing the ultrasound crystal (30) for generating a centrallydefocused ultrasound field for clearing the aqueous fluid channels ofthe eye from particles blocking these channels.